The theft of a star before his partner became a supernova

An invisible star in the eyes of researchers stole mass to his partner in a binary system before it becomes a supernova. This explosion it happened on 920 million Earthas published science this Thursday

It is assumed that the explosion resulted in a neutron star job around your compact and dense companion, which suggests that scientists first witnessed the birth of a compact binary neutron star system. This is because after the explosion all the outer layers of the star were destroyed, leaving a dense neutron starabout the size of a small town, but with more mass than the sun.

The research was led by the graduate student Kishalay De and it was mainly performed in the laboratory of Mansi Kasliwal, assistant professor of astronomy at Caltech. Kasliwal is the main researcher of the Global Relay or Observatory Watching Transients Happen (Growth) project.

Companions in a binary system

A binary star system is a system in which the two stars are connected by gravity. And what does this mean? Well, describe "stable orbits around the center of gravity of the system formed by them two ", as explained a few months ago by Professor Pilar Ruiz-Lapuente, of the Institute of Cosmos Sciences of the University of Barcelona and the Institute of Fundamental Physics of the CSIC, a Hipertextual.

The distance that the supernova has achieved has made it impossible observe to the companion of the star that has exploded. Despite the fact that you can not see it, you can "deduce the presence of a partner", explains Kishalay De Hipertextual. "We witnessed the explosion of a massive star it emitted a tiny amount of mass, which suggests that a very compact companion almost removed the entire original mass of the star by gravity, "adds De.

NASA / JPL-Caltech / R. Hurt

The candidates to be partners of this object turned into a neutron star a dwarf bank, another neutron star or even a black hole. However, the great distance that separates us makes it difficult to know for sure which of the three options is involved.

A theorized supernova

It has long been theorized with a type of supernova that was not yet present: the supernova of stripped cover. Thanks to the discovery of this binary system and the outbreak, it is now known that they can be produced.

Supernova's are bursts that occur when the star it has no more fuel to keep shining to give rise to a neutron star or a black hole. During a supernova, the dying star moves away from the material of the outer layers around it. "Usually this is the mass of the sun a few times", as explained in the press release. However, the event observed by De, Kasliwal and his team, is mentioned iPTF 14 gqr, it expelled matter only a fifth of the mass of our star.

"It has been proven through theoretical models you can get such supernova's when a massive star loses mass due to the gravitational separation of a close, compact companion (such as a neutron star, a white dwarf or a black hole), "De explains. In short, if you have a compact companion that is very close to a massive star, the gravitational forces of the compact star can detach the entire outer layer of the star. massive star to leave an ultra-stripped star behind that explodes in a supernova, "he adds.

And how was this discovery made? "It was discovered as part of the research activities of the Palomar Transitory Intermediate Factory (iPTF)," explains De. "IPTF operated from the 48-inch Schmidt telescope at the Palomar Observatory in California, using a wide-area camera that scanned the air on transients that appeared overnight, one of the main objectives of iPTF was to find supernovae and to follow in very young stadiums to try to specify the properties of their ancestor stars, so then when the researchers crossed the road with iPTF 14gqr they launched a global campaign to obtain observations using telescopes from all over the world. "These data were crucial, gave us the opportunity to point out the nature of the exploding star and suggest that it was an ultra-stripped supernova," he adds.

Away from the collision

Researchers who have observed this phenomenon theorize that the new neutron star is on track to collide with its binary system partner. So probably a merger between these two celestial bodies will cause an explosion.

"We can not know when it will happensince we have no restrictions on what the job variety of the binary number was after the supernova ", for the question when it will happen, however," qualitatively "clarifies that" it should happen. "" When the super-supernova supernova left behind a neutron star in orbit around its compact companion, it is expected that the loss of energy due to the emission of gravitational waves will bring the binary system closer and finally they merge with an explosion (similar to the event that LIGO observed in 2017, also known as GW170817) ", concludes the lead researcher of this study.

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